静叶倾斜对双级轴流风机性能和噪声影响的数值研究

以某600 MW机组配套的两级轴流风机为研究对象,采用Fluent软件对其进行三维数值计算,研究了静叶倾斜对风机性能和噪声的影响。结果表明：当正倾斜角度15°时,在设计工况风机效率提高0.09%、全压降低0.36%;静叶正倾斜角度大于25°或反倾斜时,风机效率和全压均降低。静叶正倾斜使两级静叶区的总声压级均有所降低,正倾斜15°时在设计工况点第2级静叶区总声压级降低4.4 dB,且倾斜角度越大降噪效果越显著;静叶反倾斜后,第1级静叶噪声基本不变,第2级静叶区总声压级增大2.5 dB。综合分析静叶倾斜对风机性能和噪声的影响,静叶正倾斜15°为最优方案。     

电站风机转子出厂平衡方法

介绍出厂前风机转子的平衡方法。根据转子速度及转子的宽度与直径之比的大小进行单面静平衡或双面动平衡校准,从而实现风机理想平衡状态。     

斜扭静叶的气动研究与应用

本文提出了根部反扭，顶部正扭，再复合以正倾斜的斜扭静叶是用全三元，气支变分有限元方法设计的新一代静叶，其气动性能可以马刀形弯扭静叶相媲美，而它的工艺性比马刀形叶片优越，可以用一般的通用机床加工。该斜扭静叶具有气动性能的优良，工艺简便的双重点特点，对提高我国汽轮机的经济性能与制造水平有重要意义，具有广泛应用前景。     

1000MW超超临界机组三大风机的选型分析

国内进口的首台900MW超临界机组已经投产，目前我国自行设计、制造的1000MW超超临界火电机组正处于设计和安装阶段。对于锅炉的一次风机、送风机和引风机选型，业内人士有着不同的看法。该文通过对三大风机的技术和经济性进行比较和分析，提出对于一次风机和送风机宜考虑采用动叶可调轴流式风机，对于引风机宜考虑采用静叶可调轴流式风机。     

浅谈城轨车辆静动调试验线的规划设计

介绍了中国北车集团大连机车车辆有限公司城轨车辆静动调试验线的规划设计。规划设计的城轨车辆静动调试验线由静调试验线、动调试验线及牵引变电所构成，可进行型式试验、性能试验、通信信号试验、车载试验等，具备综合检测功能。     

轴流风机通用性能数学模型

鉴于现有的动叶调节或静叶调节轴流风机性能数学模型静态精度不高,动态调节过程特性与实际 风机相差较大的问题,根据动（静）叶调节轴流风机静态性能曲线特点,依据风机的有关定律和原理,建立了动（静）叶调节轴流风机的功能通用数学模型,算例与应用实践表明：模型和静态精度,动态调节特性好,可用于轴流风机的实时仿真,性能在监测,故障预报等,具有广泛适用性。     

变截面叶片倾斜及后置叶列对静叶出口流场的影响

通过对小径高比环形静叶栅出口流场的详细测量、讨论了变截面叶片倾斜对叶栅气动性能的影响以及后置叶列引起静叶出口流场的变化，阐明了为消除大气压对出口流动参数的影响，在静叶后设置模拟动叶的必要性。     

透平双列调节级气动特性研究和分析

对采用静叶栅部分进汽的双列调节级进行不同负荷分配的气动性能分析研究，同时分析静叶栅不同局部进汽对级性能的影响。运用全三维数值方法对全周双列调节级模型计算模拟。分析结果表明，首列叶栅负荷比的变化直接影响整级的气动性能，首列叶栅负荷从80%下降到50%的过程中，级效率呈现先上升后下降的趋势，即双列调节级存在一个最佳的首列载荷分配值。同时研究首列静叶栅和第二列静叶栅部分进汽度的设计，经研究，第二列静叶栅部分进汽度与首列静叶栅部分进汽度接近时，双列调节级的气动性能最优。     

变量泵在内燃机车静液压系统中的运用

为了更加有效地控制内燃机车静液压系统中静液压马达的转速，探讨运用一种新型的控制方式，通过控制变量泵的流量来控制静液压马达和冷却风扇的转速，以提高内燃机车静液压系统的可靠性。     

核电600MW汽轮机末级空心静叶去湿缝设计研究

介绍了一种实用的空心静叶去湿缝设计方法应用于１台核电６００ＭＷ汽轮机的末级。针对该汽轮机低压缸的工作条件及通流部分结构尺寸，分别采用流线曲率法和时间相关法计算了其末级静叶前轴向间隙内和静叶栅通道内的流场；采用经验方法估计了静叶栅前的汽流湿度分布，雾滴及二次水滴的尺寸分布以及２种水分的质量比例；采用轨迹法计算并分析了水滴在静叶栅中的运动，沉积规律；基于以上结果，确定了末级静叶去湿缝的合理布置位置，形     

Ash-forming elements in four Scandinavian wood species. Part 1: Summer harvest

Woody biomass in Finland and Sweden comprises mainly four wood species: spruce, pine, birch and aspen. To study the ash, which may cause problems for the combustion device, one tree of each species were cut down and prepared for comparisons with fuel samples. Well-defined samples of wood, bark and foliage were analyzed on 11 ash-forming elements: Si, Al, Fe, Ca, Mg, Mn, Na, K, P, S and Cl. The ash content in the wood tissues (0.2–0.7%) was low compared to the ash content in the bark tissues (1.9–6.4%) and the foliage (2.4–7.7%). The woods’ content of ash-forming elements was consequently low; the highest contents were of Ca (410–1340 ppm) and K (200–1310), followed by Mg (70–290), Mn (15–240) and P (0–350). Present in the wood was also Si (50–190), S (50–200) and Cl (30–110). The bark tissues showed much higher element contents; Ca (4800–19,100 ppm) and K (1600–6400) were the dominating elements, followed by Mg (210–2400), P (210–1200), Mn (110–1100) and S (310–750), but the Cl contents (40–330) were only moderately higher in the bark than in the wood. The young foliage (shoots and deciduous leaves) had the highest K (7100–25,000 ppm), P (1600–5300) and S (1100–2600) contents of all tissues, while the shoots of spruce had the highest Cl contents (820–1360) and its needles the highest Si content (5000–11,300). This paper presented a new approach in fuel characterization: the method excludes the presence of impurities, and focus on different categories of plant tissues. This made it possible to discuss the contents of ash element in a wide spectrum of fuel-types, which are of large importance for the energy production in Finland and Sweden.     

NEXT GENERATION ENGINEERED MATERIALS FOR ULTRA SUPERCRITICAL STEAM TURBINES

正1 ABSTRACT To reduce the effect of global warming on our climate,the levels of CO2emissions should be reduced.One way to do this is to increase the efficiency of electricity production from fossil fuels.This will in turn reduce the amount of CO2emissions for a given power output.Using US practice for efficiency calculations,then a move from a typical US plant running at 37%efficiency to a 760℃/38.5 MPa(1 400/5 580 psi)plant running at 48%efficiency would reduce CO2emissions by 170kg/MW.hr or 25%.     

Contents in Volume 23,2014

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Aerodynamic performance effects of leading-edge geometry in gas-turbine blades

The purpose of this paper is to illustrate the advantages of the direct surface-curvature distribution blade-design method, originally proposed by Korakianitis, for the leading-edge design of turbine blades, and by extension for other types of airfoil shapes. The leading edge shape is critical in the blade design process, and it is quite difficult to completely control with inverse, semi-inverse or other direct-design methods. The blade-design method is briefly reviewed, and then the effort is concentrated on smoothly blending the leading edge shape (circle or ellipse, etc.) with the main part of the blade surface, in a manner that avoids leading-edge flow-disturbance and flow-separation regions. Specifically in the leading edge region we return to the second-order (parabolic) construction line coupled with a revised smoothing equation between the leading-edge shape and the main part of the blade. The Hodson–Dominy blade has been used as an example to show the ability of this blade-design method to remove leading-edge separation bubbles in gas turbine blades and other airfoil shapes that have very sharp changes in curvature near the leading edge. An additional gas turbine blade example has been used to illustrate the ability of this method to design leading edge shapes that avoid leading-edge separation bubbles at off-design conditions. This gas turbine blade example has inlet flow angle 0°, outlet flow angle −64.3°, and tangential lift coefficient 1.045, in a region of parameters where the leading edge shape is critical for the overall blade performance. Computed results at incidences of −10°,   −5°,   +5°,   +10° are used to illustrate the complete removal of leading edge flow-disturbance regions, thus minimizing the possibility of leading-edge separation bubbles, while concurrently minimizing the stagnation pressure drop from inlet to outlet. These results using two difficult example cases of leading edge geometries illustrate the superiority and utility of this blade-design method when compared with other direct or inverse blade-design methods.     

Hydrogen production by steam-gasification of carbonaceous materials using concentrated solar energy – V. Reactor modeling,optimization, and scale-up

A chemical reactor for the steam-gasification of carbonaceous particles (e.g. coal, coke) is considered for using concentrated solar radiation as the energy source of high-temperature process heat. A two-phase reactor model that couples radiative, convective, and conductive heat transfer to the chemical kinetics is applied to optimize the reactor geometrical configuration and operational parameters (feedstock's initial particle size, feeding rates, and solar power input) for maximum reaction extent and solar-to-chemical energy conversion efficiency of a 5 kW prototype reactor and its scale-up to 300 kW. For the 300 kW reactor, complete reaction extent is predicted for an initial feedstock particle size up to 35 μm at residence times of less than 10 s and peak temperatures of 1818 K, yielding high-quality syngas with a calorific content that has been solar-upgraded by 19% over that of the petcoke gasified.     

汽轮机数字电液调节系统挂闸异常的技术完善

分析了200MW汽轮机数字电液调节系统在运行中存在的挂闸异常问题,采取了相应的技术处理措施,且运行实践效果良好。     

新型高压共轨ECU升压模块的数字化开发与优化

为了提高喷油器电磁阀的响应速率,提出了一种基于CPLD(复杂可编程逻辑器件)应用于高压共轨ECU的数字升压模块。鉴于该升压电路结构参数多,其升压电压的恢复响应要求高等特征,基于Pspice建立了升压电路的仿真模型,研究了不同电路参数下升压模块的输出特性,全面优化了该升压模块的性能。结果显示,该升压模块的最大转换效率可以达90%以上。在柴油发动机上对ECU的试验表明,升压电压最大波动不超过10%,其恢复时间仅为1.3ms,功率管最大温升仅为41℃,满足整机运行范围内ECU的需求。     

Trace metal chemistry and silicification of microorganisms in geothermal sinter, Taupo Volcanic Zone, New Zealand

As part of a pilot study investigating the role of microorganisms in the immobilisation of As, Sb, B, Tl and Hg, the inorganic geochemistry of seven different active sinter deposits and their contact fluids were characterised. A comprehensive series of sequential extractions for a suite of trace elements was carried out on siliceous sinter and a mixed silica-carbonate sinter. The extractions showed whether metals were loosely exchangeable or bound to carbonate, oxide, organic or crystalline fractions. Hyperthermophilic microbial communities associated with sinters deposited from high temperature (92–94°C) fluids at a variety of geothermal sources were investigated using SEM. The rapidity and style of silicification of the hyperthermophiles can be correlated with the dissolved silica content of the fluid. Although high concentrations of Hg and Tl were found associated with the organic fraction of the sinters, there was no evidence to suggest that any of the heavy metals were associated preferentially with the hyperthermophiles at the high temperature (92–94°C) ends of the terrestrial thermal spring ecosystems studied.     

Assessment methods of material ageing using Sdobyrev''s creep rupture model

The physical aspects of the activation energy, in higher and high temperatures, of the metal creep process were examined. The research results of creep-rupture in a uniaxial stress state and the criterion of creep-rupture in biaxial stress states, at two temperatures, are then presented. For these studies creep-rupture, taking case iron as an example the energy and pseudoenergy activation was determined. For complex stress states the criterion of creep-rupture was taken to be Sdobyrev's, i.e. σ_red = σ₁ β + (1 − β)σ_i, where: σ₁-maximal principal stress, σ_i-stress intensity, β-material constant (at variable temperature β = β(T)). The methods of assessment of the material ageing grade are given in percentages of ageing of new material in the following mechanical properties: 1) creep strength in uniaxial stress state, 2) activation energy in uniaxial stress state, 3) criterion creep strength in complex stress states, 4) activation pseudoenergy in complex stress states. The methods 1) and 3) are the relatively simplest because they result from experimental investigations only at nominal temperature of the structure work, however, for methods 2) and 4) it is necessary to perform the experimental investigations at least at two temperatures.     

Production of hydrogen from sewage biosolids in a continuously fed bioreactor: Effect of hydraulic retention time and sparging

Hydrogen was produced from primary sewage biosolids via mesophilic anaerobic fermentation in a continuously fed bioreactor. Prior to fermentation the sewage biosolids were heated to 70 °C for 1 h to inactivate methanogens and during fermentation a cellulose degrading enzyme was added to improve substrate availability. Hydraulic retention times (HRT) of 18, 24, 36 and 48 h were evaluated for the duration of hydrogen production. Without sparging a hydraulic retention time of 24 h resulted in the longest period of hydrogen production (3 days), during which a hydrogen yield of 21.9 L H₂ kg⁻¹ VS added to the bioreactor was achieved. Methods of preventing the decline of hydrogen production during continuous fermentation were evaluated. Of the techniques evaluated using nitrogen gas to sparge the bioreactor contents proved to be more effective than flushing just the headspace of the bioreactor. Sparging at 0.06 L L min⁻¹ successfully prevented a decline in hydrogen production and resulted in a yield of 27.0  L H₂ kg⁻¹ VS added, over a period of greater than 12 days or 12 HRT. The use of sparging also delayed the build up of acetic acid in the bioreactor, suggesting that it serves to inhibit homoacetogenesis and thus maintain hydrogen production.